CN102414449A

CN102414449A - Vacuum pump

Info

Publication number: CN102414449A
Application number: CN2010800189225A
Authority: CN
Inventors: E.U.奥科罗亚富尔
Original assignee: BOC Group Ltd
Current assignee: BOC Group Ltd; Edwards Ltd
Priority date: 2009-04-29
Filing date: 2010-03-31
Publication date: 2012-04-11
Anticipated expiration: 2030-03-31
Also published as: JP2012525534A; GB0907298D0; TW201102518A; WO2010125368A2; WO2010125368A3; TWI489043B; KR20170063990A; US20120045322A1; BRPI1009368A2; JP5636042B2; EP2425137A2; KR20120007014A; CN102414449B

Abstract

A multi stage vacuum pump for pumping corrosive fluid with a first flow path of less corrosion material than the material of a second flow path downstream of the first flow path.

Description

Vacuum pump

Technical field

The present invention relates to a kind of vacuum pump, and relate in particular to the vacuum pump that is applicable to the pumping corrosive fluid.

Background technique

At vacuum pump known shown in Fig. 7 50, it comprises pumping mechanism 52.This pumping mechanism comprises a plurality of pumping levels 54, and these a plurality of pumping levels 54 are used for arriving between the fluid output 60 of atmospheric pressure along fluid flow path 56 pumping fluids at high vacuum fluid input 58 and rough vacuum.Five pumping levels 54 are shown.In each, motor 62 drives rotor R and rotates with respect to stator S in pumping level 54.

If the fluid of pumping comprises etching reagent,, pumping mechanism 52 is caused corrosion such as fluorine.Along with the past of time, corrosion can cause sediments accumulation on the parts surface of pumping mechanism.This can cause the operation space between the rotor R of pumping level 54 and stator S to reduce.After the pump ongoing operation long period, corrosion may cause the rotor of pumping level to contact with stator, causes failure of pump.

Can make pumping mechanism with resistant material and alleviate the corrosion in the vacuum pump, but these materials are comparatively expensive usually.

Summary of the invention

The present invention provides a kind of vacuum pump that is used for the pumping corrosive fluid; This pump comprises: pumping mechanism; It is included between high vacuum fluid input and the rough vacuum fluid output a plurality of pumping levels along fluid flow path, and wherein at the material corrosion resistance of the pumping mechanism of first section of the said flow path material less than the pumping mechanism of second section of the said flow path in said first section downstream.

In Rights attached thereto require, limit of the present invention other preferred and/or optional aspect.

Description of drawings

For the present invention is understood better, will embodiments of the invention be described referring to accompanying drawing at present, only provide embodiments of the invention with illustrational mode, in the accompanying drawings:

Fig. 1 illustrates the simplification cross section of vacuum pump;

Fig. 2 illustrates for having by the relative pump of the pumping mechanism processed of corrosion-resistant material not, with respect to the pump reference temperature, along with the corrosivity accumulation in past of time.

Fig. 3 is the pump that illustrates for having the pumping mechanism of being processed by relative corrosion-resistant material, with respect to the pump reference temperature, along with the corrosivity accumulation in past of time.

Fig. 4 illustrates for having by the relative pump of the pumping mechanism processed of corrosion-resistant material and corrosion-resistant material relatively not, with respect to the pump reference temperature, along with the corrosivity accumulation in past of time.

Fig. 5 illustrates the resistant material and the form of the character of resistant material not;

Fig. 6 is the form of instance that the composition of resistant material is shown; And

Fig. 7 is the simplification cross section of existing technology vacuum pump.

Embodiment

Referring to Fig. 1, the multistage vacuum pump 10 that is used for the pumping corrosive fluid is shown.This pumping mechanism 12 comprises a plurality of pumping levels 14, and a plurality of pumping levels 14 are used for arriving between the fluid output 20 of atmospheric pressure along fluid flow path 16 pumping fluids at high vacuum fluid input 18 and rough vacuum.Five pumping levels 14 are shown in this example.In each, motor 22 drives rotor R and rotates with respect to stator S in pumping level 14.

In order to reach the present invention, existing technology pump shown in Figure 7 is analyzed and Fig. 2 illustrates for the existing technology pump corrosion accumulation in the past along with the time (10,000 hours in this example) of being drawn with respect to the pump reference temperature.In this plotted curve, first line illustrates along flow path 56 and illustrates along the accumulation of flow path 56 at the face place of the rotor of final pumping level and stator at the accumulation at the face place of the rotor of middle pumping level and stator and second line.In this example, middle pumping level is the third level.Measure the corrosivity accumulation and degree centigrade to measure temperature with micron.Used temperature is the pump reference temperature that is obtained in final pumping level in this plotted curve.The temperature that should be appreciated that the pumping level is less than the temperature shown in the plotted curve, but also not shown for simplicity.During operation, the pump reference temperature raises and multiple factor is depended in this rising, such as the fluid type of pumping with by pump institute work.

In Fig. 7, the material of making pumping mechanism is not corrosion-resistant relatively.The instance of this material is a SG iron.The corrosivity accumulation that to find out final level from Fig. 2 significantly greater than the corrosivity accumulation of pumping level, particularly when pump reference temperature during at 200 ℃.In this reference temperature, accumulate only a little less than 400 μ m in the corrosivity of final level, and at middle rank, accumulation is only a little more than 50 μ m.

Fig. 3 illustrates the plotted curve with equivalence shown in Figure 2, and in analyzing at this, the material of making pump is corrosion-resistant relatively.The instance of this material is the SG iron of rich Ni.In Fig. 3, reduce corrosivity accumulation, but the accumulation at final pumping level place reduces about 300 μ m extremely a little less than 100 μ m, and only reduce about 30 μ m to about 20 μ m in the accumulation of middle pumping level at middle pumping level and final pumping level place.

When considering pump shown in Figure 7, when each pumping level 54 compressed fluid, 58 increase from entering the mouth to outlet 60 along the hydrodynamic pressure of flow path 56, compression ratio increases to next pumping level along flow path from a pumping level usually.The temperature of fluid and pumping mechanism also raises along flow path.

Therefore, if the fluid of pumping comprises etching reagent, such as fluorine, the etching extent that pumping mechanism 52 is caused increases and increases along with temperature and pressure along flow path 56.The pressure that increases has increased the amount of the corrosive molecules that can be used for corroding pumping mechanism and the temperature of increase has increased the corrosivity reaction.Therefore, corrosivity is accumulated in final pumping level place greater than at middle pumping level place.Therefore, owing to the operation space of locating in the final level of the maximum pumping mechanism of accumulation reduces to occur failure of pump.Though that kind as shown in Figure 3 may increase corrosion-resistantly, failure of pump usually can come across the final level place of pumping mechanism.

In pump shown in Figure 1, pumping mechanism comprises first section 24 and second section 26.Second section 26 is in first section 24 downstream.During operation, the temperature and pressure of downstream portion section 26 is greater than the temperature and pressure of upstream portion section 24.Therefore, when the pumping corrosive fluid, the corrosion of portion's section 24 is less than the corrosion of portion's section 26.Because the accumulation of corrosion deposits is less than portion's section 26 on portion's section 24 rotors and stator, the corrosion resistance that needs first section 24 is less than second section 26.Therefore first section 24 can be processed by the material relatively more cheap than the material of second section.

First section 24 and second section 26 comprise corresponding a plurality of pumping level 14.First section is adjacent with second section along fluid flow path.In Fig. 1, first section comprises the first pumping level, the second pumping level and the 3rd pumping level and second section 26 comprises the 4th pumping level and the 5th pumping level.In another was arranged, one of first section and second section can comprise single pumping level.For example, first section can comprise the first pumping level to the, four pumping levels and second section can comprise the 5th pumping level.Along with temperature and pressure is elevated to final downstream pumping level place at utmost, can make this level by resistant material, and level 1 to level 4 can be by more weak corrosion-resistant material manufacturing.Alternately, first section can comprise that the first pumping level and second section can comprise the second pumping level to the, five pumping levels.

At the plotted curve that is equivalent to Fig. 2 and plotted curve shown in Figure 3 shown in Fig. 4, it has been described for pump shown in Figure 1, with respect to the corrosivity accumulation of pump reference temperature.Fig. 4 is illustrated in 200 ℃, and the corrosivity accumulation at the final level place of pumping mechanism being decreased to a little less than 100 μ m from about 400 μ m shown in Figure 2, like the situation according to the anti-corrosive pump of Fig. 3.But, in Fig. 4, at the corrosivity accumulation at middle rank or third level place and Fig. 2 for the situation shown in the anti-corrosive pump is not identical.Thus, the corrosivity of middle rank is accumulated as about 50 μ m, and it is less than corrosivity accumulation of final level, even middle rank is processed by resistant material (for example, SG iron) not and final level is processed by resistant material (for example, rich Ni iron).Therefore, do not obtain an advantage and do like this unnecessarily increasing the pump cost from first section making pumping mechanism with resistant material and second section.

Should be first section and second section selects material to make the accumulation at the corrosive deposit at first section place be less than or equal to the accumulation at the corrosive deposit at second section place.Preferably, the parts of said pumping level by the selected material manufacturing make the corrosive gas pump period in each grade corrosion deposits be accumulated in the level with grade between equate substantially.In this way, the material that is used for various pumping levels can cost-efficient mode be selected, and keeps acceptable corrosion resistance simultaneously.In Fig. 1, the rotor R and the stator S of each pumping level 14 of second section 26 are processed by the iron of rich nickel, and the rotor R of each pumping level 14 of first section 24 and stator S are processed by SG (spheroidal graphite) iron.

At the instance of these materials shown in Fig. 5, but can select other material as requested.For example, nickel tolerance fluorine, if but the fluid of pumping comprises other etching reagent, need select suitable corrosion resistant material.In addition, first of pumping mechanism section can be processed by the material except SG iron.

If pump will be used for pumping particular etch property fluid, first section can be processed by the resistant material of the SG iron of for example rich Ni, and second section can be processed by the more corrosion-resistant material such as Cast Stainless Steel or nickel alloy.

Fig. 5 illustrates three instances of the SG iron of SG iron and rich Ni.Preferably, be the material that first section and second section select to have similar coefficient of linear expansion.Thus, Ni-res D-5S is preferred resistant material, because its coefficient of linear expansion is 12.6 m/mK, it is similar to coefficient 12.5 m/mK of SG iron.

At the composition of the SG of rich Ni shown in Fig. 6 iron material, it has good anti-corrosion matter and also has good strength and stiffness under high temperature condition.In this material, find out that nickel content is high relatively, calculate by weight 24% and 32% between.

Same or similar material is preferably used for rotor R and the problem of stator S to avoid being associated with the parts of different heat expansion coefficient in each section.

In Fig. 1, vacuum pump 10 is shown with reduced form.Vacuum pump can comprise the dried pumping mechanism of pawl type pumping mechanism or Roots pumping mechanism or other type, and wherein the operation space between the parts of pumping mechanism needs less to raise the efficiency especially.

Claims

1. vacuum pump that is used for the pumping corrosive fluid; Said pump comprises: pumping mechanism; It is included between high vacuum fluid input and the rough vacuum fluid output a plurality of pumping levels along fluid flow path, and wherein at the material corrosion resistance of the said pumping mechanism of first section of the said flow path material less than the said pumping mechanism of second section of the said flow path in said first section downstream.

2. vacuum pump according to claim 1, wherein, the respective material of said first section and said second section makes the accumulation at the corrosive deposit of said first section be less than or equal to the accumulation at the corrosive deposit of said second section.

3. vacuum pump according to claim 1 and 2, wherein, said first section and said second section are limited corresponding a plurality of said pumping levels.

4. according to each described vacuum pump in the aforementioned claim, wherein, said first section is adjacent with said second section along said fluid flow path.

5. according to each described vacuum pump in the aforementioned claim, wherein, each comprises stator and rotor in the said pumping level.

6. according to each described vacuum pump in the aforementioned claim, wherein, said pumping level or each pumping level of said second section comprise the parts of being processed by the iron of rich nickel.

7. according to each described vacuum pump in the aforementioned claim, wherein, said pumping level or each pumping level of said first section comprise the parts of being processed by spheroidal graphite cast iron.

8. according to each described vacuum pump in the aforementioned claim, wherein, the parts of said pumping level by the selected material manufacturing make said corrosive gas pump period corrosion deposits described in each grade be accumulated in level with grade between equate substantially.

9. according to each described vacuum pump in the aforementioned claim, wherein, the pumping level comprises Roots pumping mechanism or pawl type pumping mechanism.